Materials World Network: Interfacial Phenomena in Superconducting Heterostructures

本研究的目的是合成，表征，并在实验和理论上研究与复合氧化物超导体（铜酸盐），铁磁体（锰氧化物）和氧化物超导体组成的外延异质结构的界面现象相关的性能纳入场效应结构与氧化物栅极绝缘体。 这项工作结合了西班牙调查员开发的技术，（Jacobo Santamaria，Universidad Complutense，马德里）使用相对简单的高压氧溅射技术制造氧化物外延膜，美国明尼苏达州研究人员的理论和实验能力（艾伦戈德曼）和格鲁吉亚理工学院（卡洛斯萨德梅洛）以及他们在阿贡（苏珊娜特尔维尔图伊斯）和橡树岭国家实验室（玛丽亚瓦雷拉）的合作者。这一工作的统一概念是利用氧化物铁磁体的自旋和场效应门的感生电荷来研究高温超导薄膜的基态和激发态，主要有两个研究主题：（1）复合氧化物超导/铁磁异质结构中的自旋注入和相关现象;（2）复合氧化物超导纳米薄膜中的电荷效应和量子序。研究了自旋注入对铜氧化物薄膜中准粒子和凝聚态的影响，以及Andreev反射和磁邻近效应对铜氧化物薄膜中自旋弛豫时间和长度的影响。还探讨了在铁磁氧化物中诱导奇异配对态和利用场效应将赝能隙相中的“欠掺杂”铜氧化物的性质调谐到超导态的可能性。后者的努力的一个目标是调查使用场效应掺杂，以确定是否零温度之间的赝隙和超导相的边界的端点是一个量子临界点连接两个不同的超导基态。 用于解决这些问题的实验工具包括电子隧穿和电输运，以及与橡树岭和阿贡国家实验室的合作者，电子显微镜和中子散射。 所使用的理论工具涉及许多身体技术，平行和补充的实验研究。这一国际努力使来自美国和西班牙的学生和博士后同事能够进行强有力的互动，从而拓宽了年轻科学家在全球科学界的经验。该奖项与国际科学与工程办公室共同资助。

The objectives of this research are to synthesize, characterize, and study experimentally and theoretically properties associated with interfacial phenomena in epitaxial heterostructures consisting of complex oxide superconductors (cuprates), and ferromagnets (manganites) and oxide superconductors incorporated into field effectstructures with oxide gate insulators. This effort combines the techniques developed by the Spanish investigator (Jacobo Santamaria, Universidad Complutense, Madrid) for the fabrication of epitaxial films of oxides using relatively simple high-pressure oxygen sputtering techniques, with the theoretical and experimental capabilities of the US investigators at Minnesota (Allen Goldman) and Georgia Tech (Carlos Sa de Melo) and their collaborators at Argonne (Suzanne ter Velthuis) and Oak Ridge National Laboratories (Maria Varela). The unifying concepts of this effort are the use of spin from an oxide ferromagnet and induced charge from a field effect gate to study the ground state and excited states of high temperature superconducting films.There are two main research themes: (1) Spin injection and related phenomena in complex oxide superconducting/ferromagnetic heterostructures and (2) charge effects and quantum order in complex oxide superconducting nano- films. The effects of spin injection on the quasiparticles and the condensate of cuprate films and the roles of Andreev reflections and the magnetic proximity effect on the spin relaxation time and length in cuprate films are examined. The possibilities of inducing exotic pairing states in ferromagnetic oxides and using the field effect to tune the properties of an "under doped" cuprate in the pseudogap phase into the superconducting state are also explored. A goal of the latter effort is to investigate the use of field effect doping to determine whether the zero-temperature end point of the boundary between the pseudogap and the superconducting phases is a quantum critical point connecting two different superconducting ground states. The experimental tools used to address these issues include electron tunneling and electrical transport, and with collaborators at Oak Ridge and Argonne National Laboratories, electron microscopy and neutron scattering. The theoretical tools used involve many body techniques that parallel and complement the experimental investigations. This international effort allows for strong interaction of students and postdoctoral associates from the US and Spain, which broadens the experience of young scientists in the global scientific community.This award is co-funded with the Office of International Science and Engineering.